Turbine and compressor blades



Dec. 3, 1963 N. H.-KENT EIAL TURBINE AND COMPRESSOR BLADES 2 Sheets-Sheet 1 Filed Jan. 29, 1959 a G F w e F 6 2 Q m 3 4 G 2 2 I. F lll i W X HHHWWEWMIMH M m G nwwwwh w lmm nwww wm H F i m INVENTORS Qefiswz. 'vecc M:

BY bgzkgu ATTORNEYS Dec. 3, 1963 N- H- KENT ETA!- 3,112,557

TURBINE AND COMPRESSOR BLADES Filed Jan. 29, 1959 2 Shee tS-Sheet 2 F. l G. 14

INV ENTORS ATTORNEYS United States Patent 3,112,557 TURBEJE AW CGMPRESSQR BLADES Nelson Hector Kent, Allestree, and George Oswald Eecles, ilarrowford, England, assignors to Rolls-Royce Limited, Barby, England, a British company Filed Ian. 29, 1959, Ser. No. 739,829 (Ilaims priority, appl cation Great Britain Feb. 10, 1958 2 Claims. (Cl. 29-15615) This invention relates to the manufacture of blades for internal combustion turbine engines for example from metals which are resistant to high temperature such as nickel-chrome alloys.

Such blades may have passageways running axially of the blade for the flow of cooling or heating fluid such as air.

It is desirable that these passageways should provide a large scrubbing area that is to say that they should have a large internal wall area to be contacted by the cooling air.

It is also necessary to allow a substantial thickness of material between the walls of the cooling passages and the external blade surface. To reconcile these two requirements may be difficult particularly with holes near the leading and trailing edges of the blades.

This invention has for its object to provide passages through a blade which will in some measure overcome this diificulty and reconcile these conflicting requirements.

According to this invention the method of forming the blade includes (a) Producing a billet,

(b) Drilling a plurality of bores axially of the billet the cross section of such bores being initially basically circular and the distance apart of the centres of at least two of the bores being less than the sum of the radii of the bores so that the bores overlap,

(c) Inserting filler material into the bores,

(d) Extruding the billet in a die with lubrication to produce a blade section of approximately aerodynamic shape the pressure being such as to cause the bores to assume an elongated shape in cross section,

(2) Removing the filler material.

In saying that the two bores overlap we imply that the two bores are open to each other along their sides.

There may be more than two overlapping bores for example one bore may be open to two others on different sides of itself.

The overlapping bores may be of different diameters.

The remainder of the process of forming the blade can be by any appropriate method such as one of the methods described in our co-pending U.S.A. applications 689,440, 708,045, 775,638.

Preferably the overlapping bores are formed by drilling one bore, filling it with a filler material such as metal, drilling a second bore, filling the second bore with filler material such as metal, and then extruding the billet.

If more than two overlapping bores are required the above mentioned process can be repeated, filling each bore before drilling the next.

In order to reduce the possibility of sharp corners being formed further bores can be drilled with their centres in the overlapping portion of the existing bores, and to facilitate this operation hardened inserts can be put into the existing bores to guide the drill.

The centres of the bores could be positioned so that in the final blade the centres of the holes lie on the mean camber line of the blade; alternatively, for example, one bore can have its centre on the mean camber line and there can be two other bores overlapping said one bore and having their centres offset from and on opposite sides of the mean camber line and positioned inwardly of the lade with respect to the centre of the said one bore.

3,112,557 Patented Dec. 3, 1963 An example of this invention is illustrated in the accompanying drawings in which FIGURE 1 is a side elevation of a billet suitable for the production of a turbine blade embodying the invention;

FIGURE 2 is a plan of the billet seen in the direction of arrow 2 of FIGURE 1;

FIGURES 3 to 7 are plans of the billet corresponding to FIGURE 2 showing steps in the formation of the bores according to the invention; 7

FIGURE 8 is a section through an extrusion die;

FIGURE 9 is a side elevation of a finished blade;

FIGURE 10 is a section on the line llllil of FIG- URE 9;

FIGURES 11 to 14 depict enlarged portions of plans of a billet showing an alternative method of forming bores according to the invention.

In FIGURES 1 and 2, the billet 10 is shown with a number of holes 11, 12 and 13 bored in it. The holes are circular and may be bored by a conventional mechanical drilling process. The holes 11 and 13 are then filled with filler material 14 and 15 (FIGURE 3) respectively. One filler material which may be used is a mild low carbon steel. Adjacent to bore 11, an overlapping bore 16 is drilled and adjacent to bore 15 an overlapping bore 17 is drilled, as seen in FIGURE 4.

The bores 16 and 17 are then filfiled with mild steel 18 and 1? respectively as shown in FIGURE 5.

On the side of bore 11 remote from the bore 16 a further bore 20 is drilled, again overlapping the bore 11, as shown in FIGURE 6.

The bore 20 is then filled with a mild steel filler 21.

The holes 12 are then also filled with mild steel filler.

The billet is then extruded through a die 26 of the shape shown in FIGURE 8 so as to cause the bores 11, 12, 13, 16, 17 and 29 to be elongated to substantially elliptical cross-section as shown in FIGURE 10.

Before extrusion the billet is preferably nickel plated and the die surface covered with colloidal graphite as described in the application for Letters Patent No. 762,519.

The blade is then provided with a root 22, a root platform 23, a cap or tip platform 24 and bores 25 in the root 22 by a method set out in our co-pending patent applications referred to above.

It will be seen that the multiple bore 27 produced by the combination of bores ll, 16 and 24) provides a fairly large internal area at the same time maintaining a reasonable wall thickness, even at the extreme edge of the blade. Similarly, the bore 23 formed by extrusion of bores 13 and 27 provides reasonable internal wall area for a'fiow of coolant but at the same time leaves a satisfactory wall thickness at the edge of the blade.

In FIGURE 11 is shown a portion of a billet 30 in which are formed three overlapping bores 31, 32 and 33. To remove sharp corners which will result from the extrusion described with reference to FIGURE 10 it is desired to add further bores which overlap bores 31, 32 and 33.

To do this hardened inserts 34, and 36 which are made from a nickel-chrome alloy are inserted in'respective bores 31, 33 and 32 to act as guides for a drill. Two further bores are then drilled having their centres within the overlapping portions of the existing bores and their diameters determined by the arcuate inner portions of the inserts.

The inserts 34, 35 and 36 are then removed leaving a composite bore 37 as shown in FIGURE 13.

On extrusion the bore 37 is reduced to the shape shown at 37a in FIGURE 14.

We claim:

1. A method of manufacturing a blade ready for machim ng for an internal combustion turbine engine to provide a plurality of independent passageways running axially of the blade for the passage of a fluid for heat exchange which includes:

(a) producing a billet;

(b) drilling a plurality of bores axially of the billet,

the cross-section of such bores being initially basically circular, one of the bores being independently open to at least two other bores separate from each other resulting from the distance apart of the centers of said one bore and each of the other bores being less than the sum of the radii of the respective pairs of bores so that they overlap to provide substantial interconnection of the passages formed thereby, and inserting hardened metal inserts of substantially arcuate external shape in the existing three bores, each said insert having a longitudinal, parti-cylinclrical groove of the same radius as the groove in a facing insert in the overlapping bore and said grooves spaced from one another about a common center lying Within the overlapping portions of the bores, and inserting a drill using each pair of insert grooves to guide it to remove metal between the guide grooves remaining after the overlapping holes were drilled; removing the inserts;

(c) inserting filler material into the bores;

(d) extruding the billet in a die with lubrication to produce a blade section of approximately aerodynamic shape the pressure being such as to cause each of the bores to assume an elongated shape in crosssection; and

(e) removing the filler material from all of the bores.

2. A method of manufacturing a blade ready for machining for an internal combustion turbine engine to provide a plurality of independent passageways running axially of the blade for the passage of a fluid for heat exchange which includes:

(a) producing a billet;

(b) drilling a plurality of bores axially of the billet,

the cross-section of such bores being initially basically circular, and the distance apart of the centers of 4 at least two of the bores being less than the sum of the radii of the bores so that the bores overlap to provide substantial interconnection of the passages formed thereby; and inserting hardened metal inserts of substantially arcuate external shape in the existing two overlapping bores, each said insert having a longitudinal, parti-cylindrical groove of the same radius as the groove in the facing insert in the overlapping bore and said grooves spaced from one another about a common center lying within the overlapping portion of the bores, and inserting a drill using the pair of insert grooves to guide it to remove metal between the guide grooves which remained after the overlapped holes were drilled, removing the inserts;

(c) inserting filler material into the bores;

(d) extruding the billet in a die with lubrication to produce a blade section of approximately aerodynamic shape the pressure being such as to cause each of the bores to assume an elongated shape in crosssection; and V (e) removing the filler material from all of the bores.

References Qited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Australia Apr. 17, 1958 Canada Nov. 1, 1955 Germany Sept. 9, 1941 Great Britain Aug. 22, 1956 OTHER REFERENCES Hot Turbine, Flight Magazine, pages 293 and 294, volume 69, No. 2460, Mar. 16, 1956. 

1. A METHOD OF MANUFACTURING A BLADE READY FOR MACHINING FOR AN INTERNAL COMBUSTION TURBINE ENGINE TO PROVIDE A PLURALITY OF INDEPENDENT PASSAGEWAYS RUNNING AXIALLY OF THE BLADE FOR THE PASSAGE OF A FLUID FOR HEAT EXCHANGE WHICH INCLUDES: (A) PRODUCING A BILLET; (B) DRILLING A PLURALITY OF BORES AXIALLY OF THE BILLET, THE CROSS-SECTION OF SUCH BORES BEING INITIALLY BASICALLY CIRCULAR, ONE OF THE BORES BEING INDEPENDENTLY OPEN TO AT LEAST TWO OTHER BORES SEPARATE FROM EACH OTHER RESULTING FROM THE DISTANCE APART OF THE CENTERS OF SAID ONE BORE AND EACH OF THE OTHER BORES BEING LESS THAN THE SUM OF THE RADII OF THE RESPECTIVE PAIRS OF BORES SO THAT THEY OVERLAP TO PROVIDE SUBSTANTIAL INTERCONNECTION OF THE PASSAGES FORMED THEREBY, AND INSERTING HARDENED METAL INSERTS OF SUBSTANTIALLY ARCUATE EXTERNAL SHAPE IN THE EXISTING THREE BORES, EACH SAID INSERT HAVING A LONGITUDINAL, PARTI-CYLINDRICAL GROOVE OF THE SAME RADIUS AS THE GROOVE IN A FACING INSERT IN THE OVERLAPPING BORE AND SAID GROOVES SPACED FROM ONE ANOTHER ABOUT A COMMON CENTER LYING WITHIN THE OVERLAPPING PORTIONS OF THE BORES, AND INSERTING A DRILL USING EACH PAIR OF INSERT GROOVES TO GUIDE IT TO REMOVE METAL BETWEEN THE GUIDE GROOVES REMAINING AFTER THE OVERLAPPING HOLES WERE DRILLED; REMOVING THE INSERTS; (C) INSERTING FILLER MATERIAL INTO THE BORES; (D) EXTRUDING THE BILLET IN A DIE WITH LUBRICATION TO PRODUCE A BLADE SECTION OF APPROXIMATELY AERODYNAMIC SHAPE THE PRESSURE BEING SUCH AS TO CAUSE EACH OF THE BORES TO ASSUME AN ELONGATED SHAPE IN CROSSSECTION; AND (E) REMOVING THE FILLER MATERIAL FROM ALL OF THE BORES. 